- Women who are either pregnant or breastfeeding, and women of childbearing potential (i.e., has not had a hysterectomy or bilateral oophorectomy, or is not at least two years postmenopausal) who are engaged in active heterosexual relations and not using any of the following birth control methods: tubal ligation, implantable contraception device, oral, patch or injectible contraceptive, double barrier method, or sexual activity restricted to a vasectomized partner;